The shooting happened in Guamá, a poor and violent neighbourhood of the city in the Amazon region.
Local media speculated that the shooting was carried out by a gang in retaliation for the deployment in March of federal forces to Belém.
So far, no arrests have been made in connection with the crime.
Military police said seven armed men had arrived at Vanda's bar in a car and on three motorbikes on Sunday afternoon, local time.
